The present invention relates to a semiconductor unit having a semiconductor device provided on a conductive layer formed over an insulation layer.
Japanese Unexamined Patent Application Publication No. 2006-202885 discloses a semiconductor unit which can be used for example as an electric power converter. The semiconductor unit has an IGBT (insulated gate bipolar transistor) as a semiconductor device and a diode. The collector of the IGBT and the bottom electrode of the diode are soldered to a block serving to release the heat generated by the IGBT and the diode and also to connect between the IGBT and the diode. The emitter of the IGBT and the top electrode of the diode are connected by a lead.
While the semiconductor unit is being energized, electric current flows through the block and the lead, so that the block and the lead are heated. In this case, the lead is less cooled by radiation than the block that is intended to function as a radiator, which leads to the difference in the cooling between the block and the lead, that is, between the two different conductive members through which electric current flows.
The present invention is directed to providing a semiconductor unit of a structure that allows reduction of the difference in the cooling between different conductive members through which current flows.